Cell Envelope Homeostasis in Bacillus subtilis

项目摘要 细菌被细胞膜包围，这对生长、完整性和致病性至关重要。的 包膜和构建它的生物合成途径也是我们许多最有效的抗生素的靶点 和疫苗疗法。由于细胞包膜生物发生一直是一个如此成功的目标，它一直是一个 半个多世纪来的活跃研究领域。大多数负责合成和重塑的基因 的不同的表面聚合物已被确定和其生化活性的特点。然而，在这方面， 我们对这些不同的组装途径是如何相互调节和协调的理解 增长仍然有限。 这项提案集中在两个悬而未决的问题，有关细菌如何协调包膜组装， 两者都主要集中在细胞壁肽聚糖（PG）上。细胞生长需要PG的合成， 细胞壁水解酶的活性，以允许PG网络的扩展。这些潜在的溶解酶是如何 在所有细菌中，与生长的调节和协调仍然是一个未回答的问题。前两个目标 该建议集中于模式革兰氏阳性菌枯草芽孢杆菌如何调节两种功能 多余的细胞壁水解酶，以及它如何协调它们的活动与细胞壁合成和包膜 扩张.第三个目标集中在细胞如何感知和响应细胞壁生物发生的扰动。的 σ M信号通路在二十多年前被确定为一种应激反应通路， 环境压力，包括细胞壁靶向抗生素。这条通路在中间水平是活跃的 在细胞包膜稳态的未受干扰的生长和功能期间，监测包膜组装， 通过PG生物合成途径调节通量。这条通路感知到什么以及它是如何传导的 跨膜的信息仍然是神秘的拟议研究的结果将阐明 在包膜生物发生中的关键调控途径，并将为开发新的治疗方法提供信息。 感染.本申请的具体目的是： 目的1：阐明细胞如何感知和响应PG交联的程度，以确保适当的扩增。 细胞壁。 目的2研究生长过程中细胞壁水解与细胞壁合成的协调关系。 目的3：确定细胞如何感知和响应细胞包膜生物发生的扰动。

PROJECT SUMMARY Bacteria are surrounded by a cell envelope that is essential for growth, integrity, and pathogenesis. The envelope and the biogenesis pathways that build it are also the target of many of our most effective antibiotic and vaccine therapies. Because cell envelope biogenesis has been such a successful target, it has been an active area of research for over half a century. Most of the genes responsible for the synthesis and remodeling of the different surface polymers have been identified and their biochemical activities characterized. However, our understanding of how these different assembly pathways are regulated and coordinated with each other during growth remains limited. This proposal focuses on two outstanding questions related to how bacteria coordinate envelope assembly, both principally focused on the cell wall peptidoglycan (PG). Cell growth requires PG synthesis but also the activity of cell wall hydrolases to allow expansion of the PG meshwork. How these potentially lytic enzymes are regulated and coordinated with growth remains an unanswered question in all bacteria. The first two aims of this proposal focus on how the model gram-positive bacterium Bacillus subtilis regulates two functionally redundant cell wall hydrolases and how it coordinates their activities with cell wall synthesis and envelope expansion. The third aim focuses on how cells sense and respond to perturbations to cell wall biogenesis. The σM-signaling pathway was identified over two decades ago as a stress-response pathway that is induced upon environmental stresses, including cell wall targeting antibiotics. This pathway is active at intermediate levels during unperturbed growth and functions in cell envelope homeostasis, monitoring envelope assembly and adjusting flux through the PG biogenesis pathway. What this pathway senses and how it transduces this information across the membrane have remained mysterious. The results of the proposed studies will elucidate critical regulatory pathways in envelope biogenesis and will inform the development of new treatments for infections. The Specific Aims of this application are: Aim 1: Elucidate how cells sense and respond to the extent of PG crosslinking to ensure proper expansion of the cell wall. Aim 2 Investigate how cell wall hydrolysis is coordinated with cell wall synthesis during growth. Aim 3: Determine how cells sense and respond to perturbations to cell envelope biogenesis.